Safe Haskell	None
Language	Haskell2010

GHC.Stack.CloneStack

Description

This module exposes an interface for capturing the state of a thread's execution stack for diagnostics purposes: cloneMyStack, cloneThreadStack.

Such a "cloned" stack can be decoded with decode to a stack trace, given that the -finfo-table-map is enabled.

Since: base-4.17.0.0

Synopsis

data StackSnapshot = StackSnapshot !StackSnapshot#
data StackEntry = StackEntry {
- functionName :: String
- moduleName :: String
- srcLoc :: String
- closureType :: Word
}
cloneMyStack :: IO StackSnapshot
cloneThreadStack :: ThreadId -> IO StackSnapshot
decode :: StackSnapshot -> IO [StackEntry]

Documentation

data StackSnapshot Source #

A frozen snapshot of the state of an execution stack.

Since: base-4.17.0.0

Constructors

StackSnapshot !StackSnapshot#

data StackEntry Source #

Represetation for the source location where a return frame was pushed on the stack. This happens every time when a case ... of scrutinee is evaluated.

Constructors

StackEntry
Fields functionName :: String moduleName :: String srcLoc :: String closureType :: Word

Instances

Instances details

Show StackEntry Source #
Instance details Defined in GHC.Stack.CloneStack Methods showsPrec :: Int -> StackEntry -> ShowS Source # show :: StackEntry -> String Source # showList :: [StackEntry] -> ShowS Source #
Eq StackEntry Source #
Instance details Defined in GHC.Stack.CloneStack Methods (==) :: StackEntry -> StackEntry -> Bool Source # (/=) :: StackEntry -> StackEntry -> Bool Source #

cloneMyStack :: IO StackSnapshot Source #

Clone the stack of the executing thread

Since: base-4.17.0.0

cloneThreadStack :: ThreadId -> IO StackSnapshot Source #

Clone the stack of a thread identified by its ThreadId

Since: base-4.17.0.0

decode :: StackSnapshot -> IO [StackEntry] Source #

Decode a StackSnapshot to a stacktrace (a list of StackEntry). The stack trace is created from return frames with according InfoProvEnt entries. To generate them, use the GHC flag -finfo-table-map. If there are no InfoProvEnt entries, an empty list is returned.

Please note:

To gather StackEntry from libraries, these have to be compiled with -finfo-table-map, too.
Due to optimizations by GHC (e.g. inlining) the stacktrace may change with different GHC parameters and versions.
The stack trace is empty (by design) if there are no return frames on the stack. (These are pushed every time when a case ... of scrutinee is evaluated.)

Since: base-4.17.0.0